Northern Victoria Land terranes, Antarctica: far-travelled or local products?
Published:January 01, 2005
Franz Tessensohn, Friedhelm Henjes-Kunst, 2005. "Northern Victoria Land terranes, Antarctica: far-travelled or local products?", Terrane Processes at the Margins of Gondwana, A. P. M. Vaughan, P. T. Leat, R. J. Pankhurst
Download citation file:
The early Palaeozoic Ross Orogen in northern Victoria Land, Antarctica, consists of three major fault-bounded tectonostratigraphic terranes. Their true nature, far-travelled or local part of the accretionary collage, is under discussion. The inboard Wilson terrane (WT) consists mainly of high-grade metamorphic rocks intruded by the calc-alkaline magmatic arc of the Ross Orogen. The terrane nature of the WT is doubtful, as it appears more like the leading edge of the East Antarctic craton. The Bowers terrane (BT) comprises a mixed sedimentary-volcanic succession, beginning with volcanic rocks of island-arc character, followed by turbidites, mudstones, conglomerates and fossiliferous Middle Cambrian shallow-water sediments. The whole sequence is capped by a fluvial to deltaic quartzitic series several kilometres thick, with strong continental affinity. The combination of primitive forearc to back-arc volcanics at the bottom and mature continental sediments at the top poses a problem. The outer Robertson Bay terrane (RBT) is made up of a thick turbidite succession which, in one area, contains allochthonous blocks of fossiliferous Tremadocian limestones. All terrane boundaries appear to be distinct fault zones. The WT/BT boundary forms a deep-reaching continent-ocean suture associated with strongly sheared rock units, ultramafic lenses and high-pressure rocks. Coesite in eclogites of the Lanterman Range indicates a depth of burial of around 90 km. A green- schist-facies schist belt marks the BT/RBT boundary. The terranes contain evidence for subduction at an active margin setting as well as for accretion processes along major faults. The present changes of the Cambrian time-scale, such as younging of the base of the Upper Cambrian by about 30 Ma since the 1980s, allow separation of arc formation and later terrane accretion events.
Figures & Tables
Terrane Processes at the Margins of Gondwana
The Australide orogen, the southern hemisphere Neoproterozoic to Mesozoic terrane accretionary orogen that forms the palaeo-Pacific margin of Gondwana, is one of the largest and longest-lived orogens on Earth. This book brings together a series of reviews and multidisciplinary research papers that comprehensively cover the Australides from the Tasman orogen of eastern Australia to the Neoproterozoic and Palaeozoic orogens of South America, taking in New Zealand and Antarctica along the way. It deals with the evolution of the southern Gondwana margin, as it grew during a series of terrane accretion episodes from the late Proterozoic through to final fragmentation in mid-Cretaceous times. Global perspectives are given by comparison with the Palaeozoic northern Gondwana margin and documentation of world-wide terrane accretion episodes in the Late Triassic-Early Jurassic and mid-Cretaceous. The Tasmanides of eastern Australia, and the terrane histories of New Zealand and souther South America are given comprehensive up-to-date reviews.